X0306 4 2018-06-26 0 0001441816 MongoDB, Inc. MDB 0001719479 Horowitz Eliot C/O MONGODB, INC. 229 WEST 43RD STREET, 5TH FLOOR NEW YORK NY 10036 1 1 0 0 Chief Technology Officer Class A Common Stock 2018-06-26 4 C 0 2161 A 92161 D Class B Common Stock 2018-06-26 4 C 0 2161 D Class A Common Stock 2161 1502063 D Class B Common Stock Class A Common Stock 375000 375000 I By Trust Each share of Class B Common Stock is convertible at any time at the option of the reporting person into one share of Class A Common Stock and has no expiration date. The Class B Common Stock will convert automatically into Class A Common Stock on the same basis upon the earlier of: (i) any transfer, whether or not for value, except for certain "Permitted Transfers" as defined in the Issuer's restated certificate of incorporation, and (ii) at such time as the outstanding shares of Class B common stock represent less than 10% of the aggregate number of shares of the Issuer's capital stock outstanding. These shares are held by The ERH Family 2012 Trust for the benefit of the reporting person's children. The reporting person is the trustee of the Trust. The reporting person disclaims beneficial ownership of these securities, and the filing of this report is not an admission that the reporting person is the beneficial owner of these securities for purposes of Section 16 or for any other purpose. /s/ Alison Haggerty, Attorney-in-Fact 2018-06-28